@tanstack/db-ivm/dist/cjs/operators/reduce.cjs

Incremental View Maintenance for TanStack DB based on Differential Dataflow

"use strict";
var __typeError = (msg) => {
  throw TypeError(msg);
};
var __accessCheck = (obj, member, msg) => member.has(obj) || __typeError("Cannot " + msg);
var __privateGet = (obj, member, getter) => (__accessCheck(obj, member, "read from private field"), getter ? getter.call(obj) : member.get(obj));
var __privateAdd = (obj, member, value) => member.has(obj) ? __typeError("Cannot add the same private member more than once") : member instanceof WeakSet ? member.add(obj) : member.set(obj, value);
var __privateSet = (obj, member, value, setter) => (__accessCheck(obj, member, "write to private field"), setter ? setter.call(obj, value) : member.set(obj, value), value);
var _index, _indexOut, _f;
Object.defineProperty(exports, Symbol.toStringTag, { value: "Module" });
const graph = require("../graph.cjs");
const d2 = require("../d2.cjs");
const multiset = require("../multiset.cjs");
const indexes = require("../indexes.cjs");
class ReduceOperator extends graph.UnaryOperator {
  constructor(id, inputA, output, f) {
    super(id, inputA, output);
    __privateAdd(this, _index, new indexes.Index());
    __privateAdd(this, _indexOut, new indexes.Index());
    __privateAdd(this, _f);
    __privateSet(this, _f, f);
  }
  run() {
    const keysTodo = /* @__PURE__ */ new Set();
    for (const message of this.inputMessages()) {
      for (const [item, multiplicity] of message.getInner()) {
        const [key, value] = item;
        __privateGet(this, _index).addValue(key, [value, multiplicity]);
        keysTodo.add(key);
      }
    }
    const result = [];
    for (const key of keysTodo) {
      const curr = __privateGet(this, _index).get(key);
      const currOut = __privateGet(this, _indexOut).get(key);
      const out = __privateGet(this, _f).call(this, curr);
      const newOutputMap = /* @__PURE__ */ new Map();
      const oldOutputMap = /* @__PURE__ */ new Map();
      for (const [value, multiplicity] of out) {
        const existing = newOutputMap.get(value) ?? 0;
        newOutputMap.set(value, existing + multiplicity);
      }
      for (const [value, multiplicity] of currOut) {
        const existing = oldOutputMap.get(value) ?? 0;
        oldOutputMap.set(value, existing + multiplicity);
      }
      for (const [value, multiplicity] of oldOutputMap) {
        if (!newOutputMap.has(value)) {
          result.push([[key, value], -multiplicity]);
          __privateGet(this, _indexOut).addValue(key, [value, -multiplicity]);
        }
      }
      for (const [value, multiplicity] of newOutputMap) {
        if (!oldOutputMap.has(value)) {
          if (multiplicity !== 0) {
            result.push([[key, value], multiplicity]);
            __privateGet(this, _indexOut).addValue(key, [value, multiplicity]);
          }
        }
      }
      for (const [value, newMultiplicity] of newOutputMap) {
        const oldMultiplicity = oldOutputMap.get(value);
        if (oldMultiplicity !== void 0) {
          const delta = newMultiplicity - oldMultiplicity;
          if (delta !== 0) {
            result.push([[key, value], delta]);
            __privateGet(this, _indexOut).addValue(key, [value, delta]);
          }
        }
      }
    }
    if (result.length > 0) {
      this.output.sendData(new multiset.MultiSet(result));
    }
  }
}
_index = new WeakMap();
_indexOut = new WeakMap();
_f = new WeakMap();
function reduce(f) {
  return (stream) => {
    const output = new d2.StreamBuilder(
      stream.graph,
      new graph.DifferenceStreamWriter()
    );
    const operator = new ReduceOperator(
      stream.graph.getNextOperatorId(),
      stream.connectReader(),
      output.writer,
      f
    );
    stream.graph.addOperator(operator);
    stream.graph.addStream(output.connectReader());
    return output;
  };
}
exports.ReduceOperator = ReduceOperator;
exports.reduce = reduce;
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